Bar code technology is having a profound influence on today's retail merchandising industry. It has been driven primarily by two needs of the retailer: reduction of operational costs and improved inventory control at both local store and central distribution levels. There has been a long-felt need for an accurate and cost-effective method to automatically display the price of a bar-coded product on the shelf, which can be continually computer updated but which doesn't interfere with normal store operations.
Many prior art solutions have been offered. They have been as simple as a hard-wired network of displays (see U.S. Pat. Nos. 4,002,886; 4,139,149; 4,438,432; 4,500,880; and 4,521,677). Such designs suffer from reliability problems, are inflexible and their installation is expensive.
Other solutions have used a radio broadcast medium rather than wire for at least part of the communications link between the POS computer and the display shelf (U.S. Pat. No. 4,879,756). Other media have included infrared (U.S. Pat. No. 4,766,295). In all cases, the display device itself has been powered by battery, by hard-wired power or by a combination of both.
In the case of hard-wired power, the same cable may contain both the power wires and the signal wires used to control the display. To accommodate the needed wires, an extra channel is attached to the shelf edge. This increases the shelf size, making the display more susceptible to damage. It also creates operational risks in that many liquids in a store are conductive. Thus a spill can create a short circuit and hence cause a system failure. This arrangement also is inflexible because the electronic displays may only be used where the extra channel is installed and power is available. Finally, these installations are expensive.
Battery-powered solutions offer more operational flexibility because displays may be more randomly placed. However, batteries must periodically be replaced, an objectionable and time-consuming task in a store that may have tens of thousands of displays. Being wireless, the battery-powered units use light or radio waves as the medium for communicating the data from the computer to the shelf. Where radio waves are used, an FCC license must be obtained for each installation, causing delays in installation. In addition, frequency allocations are becoming difficult to obtain.